A Spanish judge has charged 32 suspected Islamic militants over an alleged plot to blow up the National Court in Madrid.

The charge sheet - published on Tuesday - included membership of a terrorist organisation, conspiracy to commit a terrorist act and forgery of documents.

Most of the 32 suspects were arrested in late 2004, the Spanish news agency Efe reported.

Madrid suffered train bombings in March 2004 which killed 191 people.

'Martyrs for Morocco'

One of the men charged on Tuesday was the alleged mastermind of the court plot, Mohamed Achraf, the Associated Press news agency says.

Alleged mastermind Achraf was extradited from Switzerland

Spanish authorities suspect Mr Achraf, a Moroccan national, of heading the plan to ram the court with a truck laden with 500kg (1,100lbs) of explosives.

No date has ever been given for the planned attack, nor any explosives found.

The Spanish judge delivering the indictment, Fernando Grande-Marlaska, said the attack could have killed 900 people.

The court is the base for Spain's anti-terrorist investigations.

Mr Achraf was held on immigration charges in Switzerland in August 2004 and extradited last April.

High-profile Spanish judge Baltasar Garzon, who headed the investigation, has alleged Mr Achraf set up the "Martyrs for Morocco" group in 2003 during time he spent in jail in Spain for fraud from 1999 to 2002.

Judge Garzon has said he thought the group had links to those responsible for the Madrid train bombings in 2004.